Using The S7-1500 As An Opc Ua Server; Configuring Access To Plc Tags; Managing Write And Read Rights - Siemens SIMATIC ET 200AL System Manual

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Using the S7-1500 as an OPC UA server

Enabling PLC tags and DB tags for OPC UA

OPC UA clients can have read and write access to PLC tags and DB tags if the tags are

enabled for OPC UA (default setting). For an enabled tag the check box "Accessible from

HMI/OPC UA" is activated.

The following example shows an array data block:

Enabling PLC tags and DB tags for OPC UA

This array can be read completely in one pass by OPC UA clients (see Addressing nodes

(Page 132)). The check boxes at "Accessible from HMI/OPC UA" and "Writable from

HMI/OPC UA" are activated for all the components of the array.

Result: OPC UA clients can both read and write these components.

Removing write rights

If you want to write-protect a tag, deselect the "Writable from HMI/OPC UA" option for that

tag. This removes the write right for the OPC UA clients and HMI devices.

Result: Only read access by OPC UA clients and HMI devices is possible. OPC UA clients

cannot assign values to this tag and therefore cannot influence execution of the S7 program.

Removing write and read rights

To write-protect and read-protect a tag, disable the "Accessible from HMI/OPC UA" option

for that tag (checkbox not selected). This makes the OPC UA server remove the tag from its

address space. OPC UA clients can no longer see that CPU tag.

Result: OPC UA clients and HMI devices can neither read nor write the tag.

Communication

Function Manual, 12/2017, A5E03735815-AF

OPC UA communication

9.3 Using the S7-1500 as an OPC UA server

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